COPD Flashcards
What investigations would you perform if suspecting COPD? What would they show?
- Spirometry (to observe if there’s reversibility) -> obstructive or restrictive lung disease; reversibility by bronchodilator (I.e. in asthma)
- Chest x-ray -> signs of infection, pulmonary oedema, hyper-inflation, emphysema
- ECG -> ischemic heart disease, arrhythmia, R sided heart strain secondary to underlying lung pathology
What are the hallmark features of COPD?
- Shortness of breath
- Chronic cough
- Sputum production
Name causes of COPD
Host:
- genetic susceptibility (eg. α1-anti-trypsin deficiency)
- other gene polymorphisms (eg. matrix metalloproteinases, TNF – α
glutathione S transferase)
Environment:
- tobacco smoke exposure
- cannabis
- other smokes
- mineral dusts (eg coal, cadmium)
What is the pathophysiology of COPD?
- Inflammation
- Goblet cell hyperplasia -> cough + sputum
- Airway narrowing -> breathlessness + wheeze
- Alveolar destruction -> breathlessness
Fibroblast -> Fibrosis -> obstructive bronchiolitis -> COPD
CD8+ T-cells -> emphysema -> COPD
Protease -> mucus hyper-secretion -> COPD
What are the typical symptoms of COPD?
- Smoker or ex-smoker aged > 35
- exertional breathlessness
- chronic cough
- regular sputum production
- winter exacerbations
- wheeze
What are the signs of COPD?
- tar-staining of fingers
- central cyanosis (if hypoxic or polycythaemic)
- tachypnoea
- chest hyperexpansion ‘barrel-shaped’
- reduced lateral and increased vertical chest expansion Ø paradoxical lower chest motion
- reduced breath sounds
- wheeze
- palpable liver edge
What FEV1/FVC ratio is indicative of obstructive lung disease (I.e. COPD)?
FEV1/FVC < 0.7
- No correction with bronchodilators
How is COPD severity scored?
GOLD scale = Global strategy for Obstructive Lung Disease
Stage 1: FEV1 ≥ 80% predicted
Stage 2: 50-79%
Stage 3: 30-49%
Stage 4: ≤ 30%
What is seen on a chest x-ray in a patient with COPD?
Often normal x-ray
- Hyper-inflated lungs
- Flattened/low diaphragm
What is seen on a CT scan in someone with COPD?
- “holes” or bullae
- Bronchial wall thickening
What happens to the blood gases in type 1 and type 2 respiratory failure?
Type 1: pH = normal pCO2 = normal pO2 = low HCO3 = normal
Type 2: Respiratory Acidosis pH = low pCO2 = high pO2 = low HCO3 = high
What is the natural history of COPD?
- Progressive decline in lung function
- Progressive dyspnea and disability
- R ventricular failure
- Exacerbation
How does R ventricular failure (Cor Pulmonale) develop in COPD?
- Hypoxia
- Pulmonary arterial vasoconstriction
- Increased pulmonary artery pressure
- R ventricular hypertrophy
- R ventricular failure
What is the treatment for COPD?
- Lifestyle advice -> Stop smoking!
- Inhaled bronchodilators
- used for symptom relief and reduce exacerbations
- SABA (short-acting b-agonists) = salbutamol, terbutaline
- LABA (long-acting b-agonists) = salmeterol, eformoteral
- Anti-muscarinics = ipratropium, tiotropium - Inhaled corticosteroids
- Reduced exacerbation frequency (if > 2/yr)
- Slows disease progression?
- Only used for severe/frequent exacerbations (if FEV1 < 50%)
- I.e. Beclomethasone, Budesonide, Fluticasone - Oral theophylline
- Bronchodilator with narrow therapeutic window
- I.e. aminophylline - Mucolytics (i.e. carbocystine)
- Reduced mucus production - Surgical procedures
- bullectomy
- Lung volume reduction surgery
- Lung transplantation - End-of-life care
What are some complications of COPD?
- Exacerbations
- Pneumonia
- Pneumothorax
- R ventricular failure (Cor Pulmonale)
- Peripheral neuropathy
- Cachexia
How would you treat an acute exacerbation of COPD in hospital?
- Oxygen (give to maintain SpO2 between 88-92%)
- High dose SABAs usually nebulised (I.e. salbutamol)
- High dose corticosteroids (prednisolone 40mg/day for 7d)
- Antibiotics If purulent sputum or very severely ill
- Reassess after 1h: if still respiratory acidosis then consider all of the following
1. IV bronchodilator (salbutamol or theophylline)
2. Urgent intensive care opinion
3. Non-invasive ventilations
4. Intubation + assisted ventilation (I.e. CPAP)
Outline the 3 lung function tests
- Spirometry -> measures the amount of air volume that you breathe in and out
- VC = vital capacity ~ FVC (forced vital capacity
- VC = volume of air that you can exhale after a full inspiration. FVC = volume of air you can forcibly exhale after the deepest breath possible. Usually very similar.
- FEV1 = Volume of air that you can forcibly exhale in 1s - Lung Diffusion Test -> provides info about how well the oxygen that you inhale moves into your bloodstream
- Inhale CO, hold breath for a few sec, then exhale
- Inhaled [CO] compared to exhaled [CO]. Results = diffusion capacity of the lungs for CO (DLCO)
- DLCO < 55% normal value = lungs do NOT efficiently absorb O2 - Lung Plethysmography -> determines how much air is in your lungs when you exhale
- restrictive = difficulty inhaling, while obstructive = difficulty exhaling
- FRC = how much air is left in the lungs after normal exhalation
- ERV = additional air forcibly expired after normal expiration (higher than expected in obstructive and decreased in restrictive)
- TLC = total lung volume
What is the pathophysiology of asthma?
Reversible airway obstruction:
- Bronchocostriction
- Bronchial mucosal oedema
- Mucus plugging
- > Inflammatory response initiated by triggers + mast cell degranulation
Name 3 bronchodilators
- Synpathomimetic agents
- Xanthines
- Magnesium
Define COPD
Lung disease characterised by chronic obstruction of lung airflow that interferes with normal breathing and is not fully reversible.
Main features include:
- Bronchoconstriction
- Mucosal oedema
- Mucosal hypersecretion
Describe how sympathomimetic agents act on bronchial smooth muscle
B2 adrenoreceptors agonists = activation of SNS = bronchodilation
- ATP turns into cAMP by adenyl cyclise = relaxation of bronchial smooth muscle
Muscarinic ACh receptors = activation of PSNS = bronchoconstriction
Name examples of short-acting and long-acting B2 agonists
Short Acting:
- Salbutamol = ventolin, airomir, salamol easi-breath
- Terbutaline = Bricanyl
Long-acting:
- Salmeterol = serevent
- Formoterol = oxis
List 6 side effects of B2 agonists
- Tachycardia
- Arrhythmia
- Myocardial ischemia
- Tremor
- Paradoxical bronchospasm
- Hypokalemia
Describe how anticholinergic drugs work
Anticholinergic drugs inhibit bronchoconstriction by antagonising muscarinic receptors of the PNS
Name examples of short-acting and long-acting anticholinergic drugs
Short-acting:
- Ipratropium bromide = atrovent
Long-acting:
- Tiotropium = spiriva
What are 3 side effects of anticholinergic drugs? In what conditions should these drugs be used with caution?
- Dry mouth
- Nausea
- Headache
Use in caution:
- Prostatic hyperplasia + bladder outflow obstruction
- Susceptible to glaucoma
Describe how xanthines work
Xanthines are phosphodiesterase inhibitors which raise intracellular cAMP -> increased bronchodilation
List examples of xanthines
Theophylline (M/R tablets)
- Nuelin SA
- Slo-phyllin
- Uniphyllin continus
Aminophylline
- Theophylline + ethylenediamine (increased water solubility allowing IV preparation)
- Phyllocontin continus (M/R tablet)
What are 6 side effects of xanthines? What drug interactions are important to note?
- Tachycardia
- Arrhythmia
- Agitation
- Convulsions
- Hypokalemia
- Levels can increase in sepsis + viral infections
Interactions (hepatic metabolism):
- Ciprofloxacin + OCP reduce clearance of xanthines
- Anticonvulsants increase clearance of xanthines
What anti-inflammatory agents are used in COPD?
- Corticosteroids
- Leukotriene receptor antagonists
- Sodium cromoglycate
How do corticosteroids work in COPD? List some inhaled, oral, and IV examples
Broad anti-inflammatory effect
- Inhibition of production of inflammatory cytokines
- Reduced hyper-reactivity of airways
Inhaled:
- Beclomethasone
- Fluticasone
- Budesonide
Oral:
- Prednisolone
IV:
- Hydrocortisone
What are the side effects of corticosteroids?
Inhaled = fewer systemic effects than oral
- Candidiasis
- Hoarseness
- Adrenal suppression
- Osteoporosis
- Growth restriction in children
Name 2 combined therapies of corticosteroids with LABA
- Salmeterol + Fluticasone = Seretide
2. Budesonide + Formoterol = Symbicort
How do leukotriene receptor antagonists work? Name an example
Leukotrienes are synthesised by a variety of inflammatory cells in the airway (I.e. eosinophils, mast cells, macrophages and basophils)
Leukotriene receptor antagonists block the binding of LTD4 to its receptor on target tissues
Example = Montelukast (singulair)
How does sodium cromoglycate work in COPD?
Mode of action not completely understood
May inhibit degranulation of mast cells
Less effective than inhaled corticosteroids
How is Omalizumab used in COPD?
Monoclonal antibody that binds IgE
Add on therapy in severe persistent allergic asthma
Fortnightly SC injections
If no response after 16 weeks, discontinue
How are mucolytics used in COPD? Name an example
Facilitate expectoration by reducing sputum viscosity
- Carbocisteine
- Anti-inflammatory properties
- Aids regeneration of damaged mucosal cells
Outline the management of chronic asthma
Step 1: PRN inhaled B2 agonist
Step 2: Add inhaled steroid (200-800mcg/day)
Step 3: Add LABA, +/- increased steroid dose to 800mcg/day; Consider leukotriene receptor antagonist or SR theophylline
Step 4: Further increase inhaled steroid up to 2000mcg/day; Add 4th drug (leukotriene receptor antaogonist, SR theophylline, or B2 agonist tablets)
Step 5: Daily low dose oral steroid; continue high dose inhaled steroid; refer to specialist
How do you assess an acute exacerbation of asthma?
Life threatening:
- PEF < 33% best or predicted
- SpO2 < 92%
- PaO2 < 8kPa
- Silent chest
- Cyanosis
- Poor respiratory effort
- Arrhythmia
- Exhaustion, altered conscious level
Near fatal:
- Raised PaCO2 and/or requiring mechanical ventilation
How would you manage a patient with acute exacerbation of asthma?
Initial:
- Sit patient up
- Give high flow oxygen
- Nebulised B2 agonists every 15min
- Nebulised ipratropium (repeat every 4h)
- Steroids: prednisolone (40mg), hydrocortisone (100mg)
If not responding:
- Magnesium (1.2-2g IV over 20min)
- Consider IV aminophylline or B2 agonists
What treatments are used for asthma, COPD or both?
B2 agonists, Ipratroprium, inhaled corticosteroids and tablet corticosteroids are used for both asthma and COPD. In practice, theophylline is not as commonly used for asthma as it is for COPD, but can be indicated in difficult cases. Magnesium typically is used for treating an acute exacerbation of asthma, and rarely used in an acute exacerbation of COPD.
Leukotriene receptor agonists are only used in asthma, whereas carbocisteine is only used to aid sputum production in COPD, again rarely in Severe Asthma. Sodium cromoglicate is only used for asthma.
Can you give some examples of each of the generic names for:
ICS
LABA
LAMA
Combination Inhaler
ICS: Clenil, QVAR, pulmicort, Flixotide
LABA: Serevent
LAMA: Spiriva
Combination inhaler: Seretide, Symbicort, Fostair
What is the difference between Type 1 and Type 2 respiratory failure?
Type I respiratory failure is also known as hypoxaemic failure, and is defined by a PaO2 of less than 8kPa. It indicates a serious underlying pathology with the lungs such as infection, oedema or a shunt.
Type II respiratory failure is also known as ventilatory failure, results when PaCO2 is more than 7. Reduced ventilatory effort can be a result of gas trapping, such as in COPD and severe asthma, due to chest wall deformities, muscle weakness or central causes of respiratory depression.
What is the pathological process that leads to Type II respiratory failure in COPD? What physiological compensatory mechanisms occur in the body to reduce the level of acidaemia?
In COPD the elastic recoil of the lungs is lost. This causes gas trapping and reduced excretion of carbon dioxide. In the blood, the carbon dioxide combines with water to form carbonic acid. In an acute setting, the increased acid levels in the blood would lower the pH levels and the patient would become unwell very quickly. However when carbon dioxide retention is progressive, as if often the case in chronic COPD, the body can compensate for this by utilising the bicarbonate buffer system of the blood. The kidneys are stimulated to reabsorb more bicarbonate, which acts as a base and neutralises the carbonic acid, thus restoring the pH back to the normal range.
What are the clinical features of hypercapnia?
- Dilated pupils
- Bounding pulse
- Hand flap
- Myoclonus
- Confusion
- Drowsiness
- Coma
What are the normal ABG values?
PaO2 = 10-13kPa
pH = 7.35-7.45
PaCO2 = 4.5 - 6.0kPa
HCO3- = 22-26kPa
Base excess = -2 to +2
What PaO2 value indicates hypoxia?
< 8kPa
How do you calculate the A-a gradient and what is the normal value?
PAO2 (alveolar oxygen) - PaO2 (arterial oxygen) = A-a gradient
Normal A-a gradient = 10
- If > 10 = lung problem (if O2 levels are ≤ 50%)
How long does respiratory/metabolic compensation take to occur?
Respiratory compensation = quick
Metabolic compensation = days to weeks (if you see this this means the patient has chronic respiratory pathology)
What are the main differences between CPAP and NIV (BiPAP)?
CPAP:
1. High flow + PEEP
- Recruits alveoli
- Corrects V/Q mismatch
- Used in Type 1 respiratory failure (I.e. pneumonia, sleep apnea, atelectasis, congestive heart failure)
NIV:
- Inspiratory push behind each breath + PEEP
- Increases tidal volume + decreases CO2
- Used in Type 2 respiratory failure (I.e. COPD + asthma exacerbation)
Name 5 clinical and pathological features of COPD
- Breathless on exertion
- Hyperinflated chest
- Wheeze
- Regular sputum production
- Smoker/ex-smoker
You are undertaking a medication review on one of your patients in a GP surgery. You note that the latest spirometry shows an FEV1 of 59%. The patient is already taking salbutamol prn. What other medications should be considered at this point?
- Tiotropium inhaler
2. Salmeterol inhaler
What clinical features are associated with an exacerbation of COPD?
- Increased breathlessness
- Increased production of sputum
- Increased wheeze
Name the class of drugs for the following:
- Salbutamol
- Theophylline
- Magnesium
- Prednisolone
- Ipratropium
Salbutamol = B2 agonist
Theophylline = Phosphodiesterase inhibitor
Magnesium = Ca2+ agonist
Prednisolone = Changes nuclear transcription of cells to reduce inflammation
Ipratropium = anticholinergic antagonist
What are the 5 most common infective causes of exacerbations of COPD?
- Strep. Pneumonia
- Viruses
- Moraxella catarrhasis
- H. influenzae
- Pseudomonas aeruginosa
When is long term home oxygen therapy (LTOT) indicated in patients with COPD?
PaO2 < 7.3kPa on room air
Practice prescribing an appropriate ‘handihaler’ for a patient known to use it for treatment of his COPD, selected from the list below. The patient has no known drug allergies.
Tiotropium 18mcg handihaler, 1 puff, INH
What kind of infection is associated with high neutrophil counts and a very high CRP?
Bacterial infection
What are 2 side effects of ipratropium?
- Worsening glaucoma
2. Urinary retention
What is the definition of an infective exacerbation of COPD?
- An increase in volume of sputum
2. An increase in purulence of sputum
What are the 3 main causes of a wheeze?
- COPD
- Heart Failure
- Pulmonary oedema
What occurs to pupil size with CO2 retention?
Pupil size increases as CO2 causes vasodilation
Name 4 causes of hypercapnic respiratory failure
- Opioid toxicity
- CVA
- Post-polio
- Scoliosis
Due to alveolar hypoventilation
What type of respiratory failure occurs in pneumonia?
Most commonly type 1 unless there’s a loss of consciousness then type 2
List 8 contraindications for NIV?
- GCS < 8 (confusion)
- pH < 7.25
- Somnolence, agitation, lack of co-operation
- High risk of gastric aspiration (vomiting)
- Facial trauma/deformity
- Recurrent gastro-esophageal surgery
- Untreated pneumothorax
- Pneumonia
What are 3 indications for NIV? What is important to remember with NIV?
- Respiratory acidosis despite controlled oxygen therapy
- Moderate to severe breathlessness with accessory muscle use and paradoxical abdominal movement
- Respiratory rate > 22
Remember:
- Need regular ABGs
- Usually used just for COPD condition not I.e. pneumonia, heart failure
Name 2 signs of hypercapnia?
- Asterixis (flapping tremor)
2. Drowsiness
What is the Venturi principle?
Bottom of mask draws in a fixed amount of air so you know the proportion of oxygen going into the mask
25, 28, 35, 40, 60% = blue, white, yellow, red, green
